Magnetic electron multiplier switch



Sept 10, 1957 F. L. ADAMS 2,806,141

MAGNETIC ELECTRON MULTIPLIER SWITCH ATrOP/vgv Sept. 10, 1957 F. ADAMSMAGNETIC ELEcTRoN MULTIPLIER SWITCH 2 Sheets-Sheet 2 Filed June 3, 1954Y JNVENTOR.

Ff /V/Q L. Agn/15 UnitedStates Patent Oce 2,805,141 Patented Sept.. 10,1.957

MAGNETIC ELECTRON MULTIPLIER SWITCH Franklin L. Adams, Detroit, Mich.,assigner to Bendix Aviation Corporation, Detroit, Mich., a corporationof Delaware Application .lune 3, 1954, Serial No. 434,148

'7 Claims. (Cl. Z50-27) This invention relates to switches and moreparticularly to high speed electronic switches.

lnrecent years electronic switches have gained importance because of thehigh switching `speeds that must be provided in the iield ofelectronics. Although relatively high switching speeds have beenattained in certain types of electronic switches, extremely highswitching speeds as may be required for certain applications have beenlheretofore unattainable. For example, electronic switches presentlyavailable cannot be reliably used to provide switching action forelectrical signals on the order of megacycles or more.

This invention provides a switch for operating in a simple and reliablemanner in response to electrical irnpulses of extremely highfrequency.The invention includes a magnetic electron multiplier in which rst andsecond series of electrical impulses are applied to first and secondgrids, respectively, to modulate streams of electrons iiowing throughthe grids. A third grid positioned at an intermediate point between theiirst and second grids has voltages of opposite polarity applied to itto alternately pass and block the electrons flowing through the firstand second grids, In this way, the electrons flowing through the irstand second grids are alternately detected by an electrode positioned toreceive the electronsowing through the irst grid during the period thatthe third grid passes the electrons and to receive the electrons flowingthrough the second grid during the period that the third grid is at apotential to block the passage of any electrons.

An object of this invention is to provide a switch.

Another object of this invention is to provide an electronic switch.

A further object of this invention is to provide for the use of amagnetic electron multiplier as an electronic switch.

Still another objectis to provide an electronic switch of the abovecharacter which is reliable in its operation and is capable of providingswitching action at relatively high speeds. f

A still further object is to provide an electronic switch of the abovecharacter in which lirst and second electron streams are modulated bylirst and second series of signals, respectively, and are alternatelypassed and blocked by a grid which is provided with an alternatingpotential.

Other objects and advantages will become apparent from a detaileddescription of the invention and from the appended drawings and claims.

" in the drawings: i

`Figure l is a somewhat schematic view partly in block form and partlyin perspective illustrating one embodiment ofthe invention.

` Figure 2 is a top plan view of `the electron multiplier shown inFigure 1, illustrating the paths of electron ow upon a biasing of anelectrode in the multiplier in a first direction. X

Figure 3 isa top plan view of the electron multiplier 2 shown in Figurel, illustrating the paths of electron flow upon a biasing of anelectrode in the multiplier in a second direction.

In one embodiment of the invention a container 10 which may besubstantially rectangular in shape, is connected to ground. Disposedwithin the container 10 at its left end is means for emitting electronssuch as a cathode 12. The cathode 12 is positioned to emit electronstowards a grid 14 when the cathode is heated. Positioned at the rightend of the container 10 is a cathode 16 which is disposed to emitelectrons towards a grid 18 when the cathode is heated.

Disposed to the right of the grid 14 is an electron multiplier generallyindicated at 20 which includes plates 22 and 24 and a plate 26 disposedin opposed relationship to the plate 24. Also included is a plate 28which faces the plate 26 and is longitudinally displaced in front of theplate 26. The grid 14, the plate 22 and the plate 24 are positioned inlaterallycontiguous relationship to one another such that the leftextremity of the plate 22 is positioned close to the right extremity ofthe grid 14 and the left extremity of the plate 24 is positioned closeto the right extremity of the plate 22. Each ofthe plates 22 and 24 aredisposed slightly to the rear of the grid 14 and the plate 22,respectively, in a progressively staggered relationship. For example,the grid 14 may be positioned approximately .225 inch in front of theback Wall of the container 10 and the plates 22 and 24 may be positionedapproximately .200 and .175 inch, respectively, from the back wall ofthe container 10.

The plate 26 is positioned in front of the plate 24 and is atsubstantially the same distance from the back wall of the container 10as is the grid 14, such as .225 inch. The plate 28 is positioned infront of the plate 26. By way of illustration, the plate 28 may bepositioned in substantially the same plane as the front wall of thecontainer 10. The plate 28 is connected to ground through a resistance30 and a detector such as an oscilloscope 32 is connected to the plate28 to indicate the electrons mpinging upon the plate.

To the left of the grid 18 is provided another electron multipliergenerally indicated at 34. The electron multiplier includes plates 36,38, 40 and 42. The grid 18 and the plates 36 and 38 are positioned inlaterally contiguous relationship to one another in the same manner asthe grid 14 and the plates 22 and 24 as previously disclosed except thatthe plates 36 and 38 are disposed slightly in front of the grid 18 andthe plate 36, respectively, in a progressively staggered relationship.For example, the grid 18 may be positioned approximately .225 inch tothe rear of the front wall of the container 10 and the plates 36 and 38may be positioned approximately .200 and .175 inch, respectively, fromthe front Wall of the container 10.

The plate 40 is positioned behind the plate 38 and is substantially thesame distance from the front wall of the container as is the grid 18,such as .225 inch. To the rear of the plate 40 is the grounded plate 42which may be positioned in substantially the same plane as the back wallof the container 10.

Positioned midway between the `plates 24 and 40 is a grid 44 which maybe approximately .200 inch from4 the back wall of the container 10. Thegrid 44 is connected through a condenser 46 to a voltage source 48 whichis adapted to provide an alternating voltage such as a square wavevoltage output.

Direct voltages are applied to the plates 22, 24, 2.6, 36, 38 and 40 toproduce a substantially constant electrical iield between the walls ofthe container 10 and the plates. Since the plates 22, 24, 26, 36, 38 and40 are positioned at dilerent distances from the walls of the container10, different voltages areapplied to the plates to produce asubstantially constant electrical iield. The voltages are Y if Y Y Y Y.2,806,141

,1jr sa. applied to the plates 22, 24, 26, 36, 38 and 40 from a p lrpower supply 50. Direct voltages are also applied to the grids 14, 18and 44 from the power supply 50 through resistances 52,154 and 56,respectively.

. The: grid 114; is connected totheoutputoi 'VatsignalY f positioningLof the pole piecesf62, thefmagnetic flux lines are substantiallyparallel Vto theplane defined by the endsV of theontainer and the fluxlines are disposed in a direction substantially perpendicular "to theelectric field provided between the plates Aand the walls of thecontainer.

Wheni the cathode'12 is heated Aelectrons are emitted by the cathodetowards theV grid 14. Upon the application of a signal to the grid'14from the source S8, the number of electrons passed by the grid' 14 arecontrolled in accordance vwithltle variations in the amplitude of thesignal. 'For example, if the signal provided is such that the grid 14becomes more positive, a proportionately increased numberV of electronsare passed by the grid 14. Similarly, if the signal provided is in adirection to decrease the potential' of the grid 14, a proportionatelydecreased number oafelectrons are passed by the grid. In this way, theintensity of thefelectron stream passed by the grid 14 is modulated inaccordancefwith the variations in the amplitude vof the signals from thesource 58.

Because of the action of the electric iield and the magnetic teld inthelregion defined by the walls of Ythe container V10, the electronspassed by the electrode 14 are made to travel in a cycloidal pathtowards the plate 22 as shown by the broken line'62 in Figure 2 of thedrawings. When the electrons impinge upon the plate 22, Vthe plate emitsa substantially proportionately increased number of elec-l tronsdepending upon the number of electrons which are passed by the grid 14to impinge upon the plate 22; The electrons emitted by the plate 22follow a cycloidal path to the plate 24 which in'turnemits aVproportionately increased number of electrons towards the grid yIf thesignal applied to the grid 44 from the source 48V is in itsYpositivewcycle at the time the electrons, emitted by the plate 24 reachthe grid 44, the electrons pass throughv the Vgrid 44 and, continue totravel in al cycloidal path `until vthey, impinge nuponthe .plate .26.VWhen the electrons Astrike :the plate 26,:theplate emits aproportionately increased numberof'electrons which impinge uponftheplate 28 for detection by theoscilloscope 32.

If the vsignalrapplied to theV grid.44.from the source 48 is in'itsnegative cycle, none ofthe electronsV emitted by the plate 24 will passthrough the grid 44. 'Instead the electrons will! be` repelled by thegrid 44 and will .travel in a Vcycloidal path to the plate 40. VTheelectrons which are `then ernittedbyl the plate 4.0 strike .plate 42andare grounded. V"The electron flow path for this condition is shownbythe broken line 64 in Figure 3.:

l The electrons emitted -by ther cathode 16 towards the grid 18 areacted upon in substantially the same manner as disclosed above inrelation to the electrons, `emittedby the V,cathode 12 vexcept thatVtheelectrons .are emitted in an opposite direction. The number ofelectrons passing through'the grid'18 are A,controlledby the variationsin the Vamplitude of thesignal applied to the gridfrom the travel in acycloidal path to the plate 38.n The plate 38 in turn emits aproportionately increased number of electrons which travel towards thegrid V44 in a direction opposite to the direction of travel of theelectrons emitted by the plate 24.

If the grid 44 is biased in aY positive direction, all of the electronsemitted by the plate 38 are passed by the grid 44 and travel in acycloidal path towards the plate y4 0. When these electrons strike theplate 40 the plate emits an increased number of electrons whichimpingeruponV and are grounded by the plate 42. If, however,'the grid 44is biased ina negative direction, the electrons emitted by the plate 38are repelled by the grid 44 and travel in a cycloidal path towards theplate 26 as shown by the broken line 68 in Figure 3. When theseelectrons im- Y pinge upon the plate 26, a proportionately increasednumber of electrons are emitted by the plate. These electrons impingeupon the Yplate 28and are detected by the oscilloscope 32. Y

When the electrons emitted by the plates 24 and 38 are passed by thegrid 44 during the period that it is biased. in a positive direction asshown in Figure 2, onlythe electrons emitted by the plate 24 reach theplate26 and Y cause the plate 26V to emit a proportionatelyincreasednumber of electrons for detection by the plate 28. Therefore, while thevgrid 44 is biased in its positive direction, the oscilloscope 32will'provide indications of the'amplitudes of the signals from thesource 58 since the intensity of the electron stream passed by the grid44 4is modulated in accordance with the amplitude of the signals.

When the grid 44 is 'biased in a negative direction as illustrated in'Figure 3, onlythe electrons emitted by the plate 38 reach the plate 26and cause a proportionately increasedv number of electrons to be emittedby the plate 26 for detection by the plate 28. The oscilloscope 32 thenprovides indications of the amplitudes of the signals Afrom the source60 since the electron stream passed bythe grid 18 is modulated inaccordance with the amplitude of the signals.

Upon an alternate biasing of the grid 44 because of an alternatingsignal, from tlie source 48,ithe plate 28 alternately detects theelectrons flowing through4 the grid .1.4

Ysource 48.

and the electrons iiowing through the grid 18. The speed at 'which theAplate V28 valternately detects the electrons owing through the grids 14and 18 is dependent upon the frequency of the alternating signalprovided by fthe In the manner described above, the apparatus disclosedactsV as an electronic switch to alternately provide indii cations ofthe amplitudes of the'signals from the sources 58 and 60, `since theelectron streams flowing through thev grids 14 and 18 are modulated inaccordance with theV signals provided' by the' sources 58Yand 60,respectively. Theafrequency at which the switching action occurs Viscontrolled by the frequency'of the signal from the source 48. Ifoprovide for the alternate detection of the signals Afromthe sources v58andl 60 at the proper instant, Vthe frequency ofthe signals-fromvthe-source 48' must be the sources 58 and 60. f v Y Forexample, if `thesignals from'the sources 58 and 60 recur at the Yrate. of one milliontimes per second, the source 48 maybe adjusted to provide a signalhaving a one (l) megac'ycle', frequency so that every otherlsynchronized to the repetitive rate the signals from signal introducedto the grids 14 and 18.from the sourcesV 58 and, 60, respectively, willbedetected by the plate 28. AIn ,tl1 isway,V .the signals froniftliesource 58 and the source 60 may be' Vviewed side'by side on the screenof` the oscilloscope 32 since the electronsowingtbrough the grids Y14andv 18 willbe detectedlat diiereiitv The apparatus disclosed aboveVhasn several important y advantages. The apparatus( may be usedVtciprovide switchingfaction at extremely high rates,` sueltasV 10megacycles or more. Furthermore, the apparatus is adaptable for use overa wide range of signals recurring at different rates because the voltagesource 48 may be synchronized to the repetitive rate of the signals fromthe sources 58 and 60. Another advantage is that relatively weak signalsmay be detected since electron multipliers 20 and 34 will amplify thesignals prior to their detection by the plate 28.

Although this invention has been disclosed and illustrated withreference to particular applications, the principles involved aresusceptible of numerous other applications which will be apparent topersons skilled in the art. The invention is, therefore, to beliimtedonly as indicated by the scope of the appended claims.

I claim:

l. In combination, means for providing a flow of electrons in first andsecond streams, means for controlling the number of electrons flowing inthe first and second streams, a grid disposed to pass the electrons inboth streams upon a biasing of the grid at a first potential and toblock the passage of the electrons in both streams upon a biasing of thegrid at a second potential, means for alternately biasing the grid atthefirst and second potentials, and a detector disposed relatively to thegrid for detecting only the electrons in the first stream upon a passageof the electrons by the grid and for detecting only the electrons in thesecond stream upon a blocking of the passage of the electrons by thegrid.

2. In combination, means for providing a flow of electrons in first andsecond streams, a first electrode disposed to pass the electrons owingin the rst stream and to control the number of electrons passed by theelectrode in accordance with variations in the potential of theelectrode, a second electrode disposed to pass the electrons flowing inthe second stream and to control the number of electrons passed by theelectrode in accordance with variations in the potential of theelectrode, a grid disposed between the first and second electrodes topass the electrons flowing past the first and second electrodes upon abiasing of the grid at a first potential and to block the passage of theelectrons upon a biasing of the grid at a second potential, means foralternately biasing the grid at the first and second potentials, and aplate disposed relative to the grid to receive only the electronsflowing in the first stream upon a passage of the electrons by the gridand to receive only the electrons owing in the second stream upon ablocking of the passage of the electrons by the grid.

3. In combination, means for providing a ow of electrons in rst andsecond streams, a rst grid disposed in the path of electron fiow in thefirst stream, means for applying a first signal to the first grid tocontrol the number of electrons flowing past the grid in accordance withthe variations in the amplitude of the signal, a second grid disposed inthe path of electron ow in the second stream, means for applying asecond signal to the second grid to control the number of electronsflowing past the grid in accordance with the variations in the amplitudeof the signal, a third grid disposed in the path of the electronsflowing past the first and second grids, means for applying a thirdsignal to the third grid for alternately passing and blocking theelectrons liowing in the first and second streams, and a plate disposedrelative to the third grid to collect the electrons in the first streamupon the passage of the electrons by the third grid and to collect theelectrons in the second stream upon the blocking of the passage ofelectrons by the third grid.

4. An electronic switch, including, means for providing a ow ofelectrons in first and second streams, means for modulating theintensity of the first electron stream in accordance with variations inthe amplitude of a first signal, means for modulating the intensity ofthe second electron stream in accordance with variations in theamplitude of a second signal, a rst plurality of plates,

one of the plates in the plurality being disposed to receive theelectrons flowing in the first stream and to emit an increased number ofelectrons, the other plates in the plurality being disposed to receiveelectrons emitted by preceding plates in the plurality and to emit anincreased number of electrons, a second plurality of plates disposed inopposed relationship to the rst plurality of plates, one of the platesin the second plurality being disposed to receive the electrons flowingin the second stream and to emit an increased number of electrons, theother plates in the plurality being disposed to receive electronsemitted by preceding plates in the pluralityand to emit an increasednumber of electrons, a grid disposed to receive, in opposite directions,the electrons emitted by the last plates in the first and secondpluralities, means for applying a biasing signal to the grid so that thegrid alternately blocks and passes the electrons received, a detectordisposed to receive the electrons emitted by the last plate in the rstplurality upon a passage of electrons by the grid and disposed toreceive the electrons emitted by the last plate in the second pluralityupon a blocking of electrons by the grid, and means connected to thedetector to alternately indicate the intensities of the electronsemitted by the last plates n the first and second pluralities.

5. An electronic switch, including, means for providing a ow ofelectrons in first and second electron streams, means for modulating theintensity of the electron flow in the first stream in accordance with afirst signal, means for modulating the intensity Iof the electron flowin the second stream in accordance with a second signal, a grid disposedto receive, in opposite directions, the electrons flowing in the firstand second streams, means for applying to the grid an alternatingvoltage so that the grid alternately blocks and passes the electronsreceived, and means disposed to detect the electrons in the first streamupon a passing of electrons by the grid and to detect the electrons inthe second stream upon a blocking of the passage yof the electrons bythe grid.

6. An electronic switch, including, electrode means, a first pluralityof plates disposed in laterally contiguous relationship to one another,the plates being disposed at different distances from the electrodemeans, means for applying different voltages to the plates in the iirstplurality to provide a substantially uniform field in the region betweenthe electrode means and the plates in the first plurality, a secondplurality of plates disposed in laterally contiguous relationship to oneanother, the plates being disposed at different distances from theelectrode means, means for applying different voltages to the plates inthe second plurality to provide a substantially uniform field in theregion between the electrode means and the second plurality of plates, afirst grid disposed in laterally contiguous relationship to a firstplate in the first plurality, a second grid disposed in laterallycontiguous relationship to a first plate in the second plurality, meansdisposed to emit a first stream of electrons towards the first grid,means for applying a first signal to the first grid to limit the numberof electrons in the first stream passed by the grid in accordance withthe variations in the amplitude of the signal, means for applying asecond signal to the second grid to limit the number of electrons in thesecond stream passed by the grid in accordance with the variations inthe `amplitude of the signal, means for providing a magnetic field tooperate in conjunction with the electrical fields produced between theelectrode means and the plates in the rst and second pluralities toproduce a cycloidal movement of the electrons passed by the first andsecond grids, the first plates in the first and second pluralities beingdisposed to receive the electrons in the first and second streams,respectively, and to emit an increased number of electrons substantiallyproportionate to the number of electrons received by the plates, theother platesgrin-thefffirst-andisecond-plnralities being Vdisposed toreeive thee1ectronsfemittedebya `preceding plate in the plurality and5to emita .substantially proportionately increased number `vofe1e`ctrons,.a third Y grid disposed between'itheilast:plates inthefrstand second pluralities and vr'disposedstoreceive;irroppositedirections, the electronsgemittedbylthelast plates in both pluralities,means forapplyingathird signal to vthe Vthird grid for biasing the:Ygn'dfto `:alternatelyfpass and Yblock the passage ofr the(electrons.`xfeceived'fbyl the grid, and a detector disposedrlativetofthethirdgrid to-receive the electrons emitted bythev last1platein the vrst plurality upon a passing of electronsibyfthegrid;andgto receive `the electrons emitted bystllelas'tl plateinsthezsecondplurality upon a blocking ofithepassageofqeleetrons by the grid. Y

V:7.'"In:eombinationga first source for providing a first Yeletronstreaxn, afsecond sorce for providing a second electron.A stream,ta :screen grid of substantially planar Ysidetlie electrons aowingrinthexsecond'ntreamrnieans for 'biasing-Ille l grid at af =rst potential5to' -provide for thezpassage of theV electrons( in the rst andseeondstreams, means forv :biasing theigri'd iat a Iseond potential sto' blockY the; passage of the-electrons 'ini therst; and-secon'destreamsV andmeans disposed relative to -thefgrid Yto"detectifrznly -2,504,321 Giaeoletto f Apr 18, .1,950

Y Y. l. Y

configuration disposed Vtoleeeive at oeside theuelectrgnsv

